These last two episodes of Magical Girl Site will be totally unknown territory for me. I’m going to guess that they’ve gone anime original for episodes 11 and 12, as I know that the manga continues on past this point. It’s entirely possible that this episode is adapted from future chapters, but I wouldn’t be able to tell you that for sure. Not without looking it up, and I’d rather wait for the official translation of the manga.
Anyways, in this episode, the magical girls have a plan that they put into action.

Mikari and Kosame keep an eye on things from the skies

The magical girls intend to capture a site administrator, and they managed to determine when one will be delivering a wand to a new magical girl. They split up into three groups. Mikari and Kosame fly on Mikari’s broom to keep an eye out, Aya, Tsuyuno and Rina hide out at the school she attends, whilst the others wait outside the girl’s home.

Site administrator Ni shows up at the school

As the magical girls anxiously wait for their prey to appear, Aya is rightfully worried about Tsuyuno using her wand. She doesn’t say anything, though. The site administrator, Ni, then arrives at the school, so the plan is put into action.

Rina attacks Ni

Rina launches a surprise attack on Ni. She is able to make the site administrator lose a leg, but then Ni starts to fight back. She is incredibly powerful, almost leveling the whole building with a single punch. She can even effortlessly stop Rina’s hammer with her hand.
It looks like Ni has the upper hand, but when she turns her attention to Aya and Tsuyuno, Rina is able to catch her off guard with a different wand. Aya then uses her wand to shoot the site administrator.

Sarina appears behind Ni

Sarina uses her wand to cut Ni into pieces. The others join her, and Rina finishes Ni off once and for all. After she dies, they discover something shocking.
As that happens, Sayuki, Asahi and Kiyoharu are rushing over to help out, but they find their way blocked.

Site administrator Hachi can multiply herself

They are attacked by Hachi, who has the ability to create clones of herself. Sayuki is entrusted with holding them off, whilst Kiyoharu reports the situation to the others.

Turns out the site administrator are human beings

After having killed Ni, the magical girls are shocked to discover that the site administrators are human beings just like them. They don’t have long to dwell on it though, as Sarina is suddenly shot down.

Nana appears

Turns out that Nana had figured out the magical girls’ plan, and used that opportunity to attack them. It is around now that Kosame hears from the other, and is encouraged to go and help them. She does so, leaving the others to deal with Nana.

Tsuyuno pays a heavy price to protect her friends

Tsuyuno steps forward to confront Nana. Aya tries to rush over to stop her, but it is ultimately pointless. Using up the last of her life, Tsuyuno uses the barrier wand to protect her friends, and Sarina’s wand to surprise Nana.
Tsuyuno manages to sever Nana’s arm, but otherwise her attack failed. As Tsuyuno life drains from her body, she tells Aya that she was grateful she met her, and that she should live strongly. The last thing she tells Aya is that she loves her.

This scene where Aya is unable to get past the barrier to be with Tsuyuno is heartbreaking

With the barrier still up, all Aya can do is cry out towards the heavens. However, this episode has one last surprise before it ends.

Tsuyuno has been chosen as a new site administrator candidate

Well, didn’t expect that. I guess being in unfamiliar territory means I get to experience twists like these for the first time.
I wonder if the site administrators retain any memories of their lives from before they were chosen… that will almost certainly be a factor in what Tsuyuno ends up doing next.
As for Aya, it’ll be interesting to see whether she will live strongly as Tsuyuno said, or fall back into the suicidal depression she had at the beginning of the season.
Aya has grown a lot since then, but she did just lose the girl she loves. We’ll just have to wait until next time to see.

Also, I lied a little about this being completely unfamiliar. Hachi’s ability was first shown in chapter 29 of the manga, so I’ve known about it for a little while. It’s entirely possible that the battle will end up going the same way as it does in the manga.

Nana shooting Sarina also happened much earlier in the manga – the episode that adapted it changed it to a warning shot. Nana knows about Sarina’s treachery much earlier on and takes actions to stop it in the manga.
That is part of the reason I feel that Sarina allying with Aya was more effective in the manga. I won’t say too much else, in case parts of those specific chapters are used for the finale.

I guess it was inevitable that Tsuyuno was going to use up her life force at some point, so I was prepared for that. However, I did not expect that to play into her becoming a site administrator candidate, and that has made me appreciate this episode even more.